To compare the number of aphereses required to harvest at least 5 x 10(6) CD34+ cells/KG actual body weight using either human stem cell factor in combination with filgastim or filgrastim alone for mobilization of progenitor cells in patients with high risk stage II, stage III, or stage IV breast cancer. To assess the safety of human stem cell factor when administered in combination with filgrastim, including the evaluation of tumor cell contamination of the leukapheresis products.